Polycarbonates are generally produced by using raw materials which can be obtained from oil resources. Because of the concern about the exhaustion of oil resources, it is desired to produce polycarbonates by using raw materials obtainable from renewable resources such as plants.
On the other hand, an ether diol expressed by the following formula (3) can be easily prepared from renewable resource, for example, polysaccharide, starch or the like.
The ether diol has three kinds of stereoisomers. In concrete terms, they are 1,4:3,6-dianhydro-D-sorbitol (hereafter, this compound will be referred as to “isosorbide” in this description) expressed by the following formula (5),
1,4:3,6-dianhydro-D-mannitol (hereafter, this compound will be referred as to “isomannide” in this description) expressed by the following formula (6),
and 1,4:3,6-dianhydro-L-iditol (hereafter, this compound will be referred as to “isoidide” in this description) expressed by the following formula (7).

Isosorbide, isomannide and isoidide can be produced from D-glucose, D-mannose and L-idose, respectively. For example, isosorbide can be produced by hydrogenating D-glucose followed by dehydration with an acid catalyst.
Heretofore, it was studied to incorporate especially isosorbide among the above-mentioned ether diols into a polycarbonate as the main monomer (for example, German unexamined patent publication No. 2938464, Journal fuer praktische Chemie, p. 298-310, vol. 334, 1992, Macromolecules, p. 8077-8082, vol. 29, 1996, and Journal of Applied Polymer Science, p. 872-880, vol. 86, 2002).
However, isosorbide-derived polycarbonates have a problem of poor moldability, which is caused by extremely high glass transition temperatures and melt viscosities due to their rigid structures.
Further, methods for producing copolycarbonates which contain isosorbide and a diphenol of various types were reported (for example, JP-A 56-110723, Macromolecular Chemistry and Physics, p. 2197-2210, vol. 198, 1997, Journal of Polymer Science: Part A, p. 1611-1619, vol. 35, 1997, and Journal of Polymer Science: Part A, p. 1125-1133, vol. 37, 1999). These copolycarbonates have problems that the diphenols are derived from oil.
On the other hand, speaking of polycarbonates which are derived from aliphatic diols, glass transition temperatures of the polycarbonates which are derived from ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or the like are 0-5° C., −35° C., −41° C. and −50° C., respectively (for example, Journal of Polymer Science: Polymer Letters Edition, p. 599-602, vol. 18, 1980, Macromolecular Chemistry and Physics, p. 97-102, vol. 199, 1998, and Polycarbonate resin handbook, edited by Seiichi Honma, Nikkan Kogyo|Shinbun|Co. p. 21, 1992).
It is possible to use renewable resources as these aliphatic diols, but aliphatic diol-derived polycarbonates are usually oily substances or solids with low melting points at the room temperature due to their flexible structures, and they have shortcomings of poor heat resistances. Polycarbonate copolymers derived from an aliphatic diol and having a higher glass transition temperature have never been reported.
Further, although reports concerning copolycarbonates of isosorbide and an aliphatic diol are few, as one of them we can find a report of copolycarbonates of an aliphatic diol such as 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol or 1,10-decanediol, and isosorbide (for example, Okada et al, Abstract of the seventh open symposium on “Polymers with low environmental loads”: Construction of a sustainable material system based on production of plastics with low environmental loads from renewable resources, Scientific Research on Priority Areas (B) supported by Grant-in-Aid for Scientific Research of Ministry of Education, Culture, Sports, Science and Technology, p. 26-29, 2002, and Journal of Polymer Science: Part A, p. 2312-2321, vol. 41, 2003).
These polycarbonates are block copolymers or random copolymers, and their glass transition temperatures become lower with increasing lengths of aliphatic chains. The temperatures have been determined as 65° C. or 59° C., 26° C. or 20° C., 12° C. or 23° C., and −1° C. or 7° C., respectively, and they are poor in heat resistances.
Further, JP-A 2003-292603, which was published after the date of the basic application of the present invention, describes a thermoplastic molding material containing a polycarbonate compound obtainable from isosorbide. Although the glass transition temperature of the thermoplastic molding material is sufficiently higher than the room temperature, further improvement of heat resistance is desired.